There are some of these which are indeed marked for comparison: a ruskin and an Astra among the red ovals. The elongated green has an interesting round indentation perhaps to help sticking onto the metal surround.
One thing I have noticed is that the glaze on the Ruskin cabochons does not seem to have spread over the edges and onto the bottom of the cabochons. The marked Astras normally have the glaze flowing onto the edges of the bottom.
I have found that there is another group that have the glaze all over. They will be on a further few postings.